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Monday, 26 September 2011

How to Make a Solar Powered Oven

Solar ovens are not a new idea. Almost 200 years ago, the British explorer John Herschel used a solar oven to cook food while in Africa. Today, it is perfectly possible to make your own solar oven from a couple of boxes and some everyday household items. A cardboard solar oven can produce temperatures in excess of 230 degrees Fahrenheit, more than sufficient to boil water and cook a meal.

Things you'll need:

15-inch-square cardboard box

17-inch-square cardboard box

Aluminum foil

Glue

Scissors or knife

Masking tape

Sheet of thick card

Sheet of glass or acrylic plastic

Newspaper or a small wooden block

Stiff wire

Instructions:

Close the top of the larger box. Rest the smaller box on top of it, in the center of the lid of the larger box, and draw around it. Remove the smaller box. The result is the outline of the smaller box drawn in the middle of the large box's lid. Cut around the line to create a hole in the lid of the larger box. When completed, the hole should be the same size as the smaller box.

Open the larger box and cover the internal surfaces, including the remains of the lid, with aluminum foil. Glue the foil into place. Close the lid and glue the flaps into place so the lid cannot be opened. Seal around the edges with tape to form an air-tight seal.

Open the lid on the smaller box. Line the box with foil, covering the entire surface apart from the lid. Fold the lid of the smaller box back on all four sides so the flaps stick out from the box.

Place folded newspaper or a small wooden block in the base of the large box so that the smaller box, when lowered into the hole, rests on the paper or block. This supports the inner box when a pot is placed in it.

Lower the smaller box into the hole and glue the lid flaps to the outer surface of the larger box's lid. The result is a large box with an inset smaller one.

Create a reflector by cutting a sheet of card to the same size as the top of the larger box. Coat one side of the card in foil and glue the foil in place. Tape the bottom edge of the reflector to the back edge of the larger box so it looks like an additional fold-down lid.

Bend both ends of two strips of stiff wire through 90 degrees to form two 6-inch-long staple-shaped metal supports for the reflector. Lift the reflector so that it stands vertically. Use tape to attach a wire prop on each side of the reflector about 3 inches above the hinged base. Tilt the reflector slightly forward from vertical so it reflects light down into the oven. Adjust the angle of the props to hold it in this position.

Cut a sheet of glass or clear plastic to fit over the top of the smaller box. This acts as a see-through lid for the oven, trapping heat inside the box. Do not attach the transparent sheet to the box; it needs to be removed when adding or removing food from the oven.